Reconstituted powdered milk products and method and device therefor



Dec. 31, 1957 l INVENToR. lAwnece A. MM@

NIEMANN United States Patent-f r. no. ....H ..,......l..- nn---.t .u

REcoNsTITUTEn rowDnREnMrLKmRonUcrs 'AND MEFHQDN ,-PEWCEJHEBEEOB APRE-negativas 17 19?. Sesialiaa 364.1511` 6 :Claims: (Cl. 991-6?) This invention relates. to .the reconstitution of powdered. mini witnginnids, sirenas iwater, 'anni ,whole mina, fluid sknn'milkorpartially'fevaporated milk,l and is directed' particularly to the production in commercial quantities'j ofylreconstituted milk products khaving lsucha degree f concentration, uniformity andy freedomtrom,sedirnerta-T tioii'and bacterial growth as to be commercially acceptable as ,eq valents of evaporatedor condensed milk, products.`

Further purposes include:

Deyelopment of a method for.reconstitutingpowdered Cintly; 10W f0 inhibit the growrhpf. bacteria;

Separating the milkgpowdernto particles by lifting the powder'insa partial vacuum, and avoidingthjforinatin" of..doughy aggregations of undissolved milk powder;

Avoiding manual agitation and foamingof the 'recon-V stituted product, and the spreading ofmilk powder as dust, by performing theprocess in an ejector-like 'closed`7 system lin thepabsence of air;4

Eecting both the SeparaQnofthe milk powder into particles and the mixing of the particles with the fluid vby means ,0fa jet stream created inra sucti'on'T; i

Carrying out suchY reconstitution processv either as a bah, process or, as a continuous .production process;- and Providing a simple, inexpensive'jdevice foi" carrying o'n milka't fholding temperaturel fordairy products,lsi11i. f

theprocess and achieving theproductsof this invention.' 40

.Incarry ing"out.the. foregoing. obects, the present invention utilizes certain new lrincipls not. heretofore knownorused in thejdairy industry, including the"`fl' lowingz.. l Y .f n

Powderedmilk may be reconstituted with a fliud `at holding temperature, on a commercial scale and with" out mechanically applied agitation.

Particles of powdered milk may be separated from each otherby lifting them in` a partialvacuumwagaistthe" force of gravity acting upon therri."l T' Particles so lifted and' separated may be presented to the cold uid and entrained in it along a high"vel`o`ity 'jet which impnges upon the particles, entrains them inifv formly dispersed andmixes them at `onc'e""into"ys`tab1e' a 4 Y j The mixing may be carried out in a closed system, freerfrom contamination 'v'en by air, and no foaming willresult.

By applying. constant pressureto the fluid stream, the

rate, of admixture -of powdered milk particles may be-` Apothemypcal, product of I e invention. vsubstinitially ind A .ishabl Lvfrjoiri ytheflirst mentioned, is a reconstituted'mixtur of'20% nnfat milk powder and 807g, cold water. The following 7siunmarization of theprocess refers'l specviically to product, but its applicationto 'the `otrijer p'rot'llu'ts of invention herein willrbe apparent. `AA batch 1otfskir'rly ilk lis reduced to holding Vtemperature of AQQEL A't this; temperaturethe growth of bacteria is inhibited, andfto carry onoperations at such temperature is an approved conservative practice in the dairy industry. Ho ver','`it"ha's Lnoti heretofore vbeenthouglit possible to com ine; powdered milkwith iiuids ofusuch low temperaon ya' ceiinfmrcial scale;` the practice -has been to elevatefftliefteniperature to or 110 Frfor the pur polslewofy in'cf'reasing'the supposedsolubilivty of the mixture. Retrningtolthe present process,A such skim milk may er pres rejandyforced through a nozzle so that- N s as ajetwstreamin thewchamberof a suction T.' The ei'ectofnthev :nozzle is to'acelerate greatly the' ow ofztheluidand reduce itsstatic pressure-below atmo's' pheric pressure,` creating suction'within the T.1 To the suctipntinlet ofthe T is attached oneend of a tube, whose otherfend may be inserted into a'container of milkvpowder, thepowdefrdwithin the container being subjected `to a'tmospher'ioi pressure.` Suction`^created Aby the uid Aje't st rfeamvwithinmthe suction' Tjdraws themilk powder into the suction tube, raising jthe powder particles against the resistanceofvgravityfand thus tending to separate them"v frorneachwoher." Thepressure "diierence between the suctionrwitghin'the T andthe atmospheric pressure conveys such particles into ythe suction 'T aroundf the j'et stream emergingfrom the nozzle.

Asrkthe jetpstreamemerges from the nozzle at high velocity, andvvv gradually broadens, it envelops' and" en#-` trains the milk powder particles, agitatingth'emvilently all@ blllillg Nthtrn into jsolution "without mechanicalmixe ing.j No air beingpresent, save 'foi the minute'quantities" of air which may have been in the powder container, there: isnojfoaming, The product emerges perfectlynecofsti'tuted., If canned and sterilized, it may he '1eft'on"th'e shelffor yas manymonths as evaporated skim"milk," with"v no greatersedimentation; that is', without any deposit'of" powder out 'of ysolution Vonto the containe'bottom Where there is 'a proper balance between'prss're on theuid, height of lift fromthe milk powderE container," and nozzle characteristics, the only attentiomreqirefd' is A to keep the end of the suction' tube buriedin"thepowdenA container. So regular is the rate of "mixture'tliat where'V such balance is achieved, the mixture emerging from" the suction T. maybe Vat the' desiredstandardlof coricentration, e. g., 20% solids not -fat'in the case being" discussed.. With such standard' achieved; thereiiieed i no recirculation of the mixture.'

However,'for many purp'osesthe use of abatch tank will add to the convenience of the operation. -f"pi-'e'.letr' mined quantity vof the cold ui'd maybe'placedn the" batch tank for mixture witha'prede'ter'mied 'quantityof" milk powder, and the product emerging from the suction T returned'to the batch tank.v Usingsuch a'batch tank", the" circulation throughthe system "is lcontinued'a sufcient" timeto incorporate the powder in solution;v and the n'i's'hed or system of apparatus for carrying out the method and making the products of this invention.

Figure 2 is an enlarged fragmentary sectional view of the T and nozzle shown in Figure 1.

Figure 3 is a diagrammatic sketch of a system of apparatus alternative to the embodiment shown in Figure 1.

Reference will now be made to the parts of the drawings according to their designation by reference numerals.

Fluid at holding temperature is obtained from a supply source (not shown) and drawn from a supply pipe 1 through a three-way valve 2 and a down pipe 3 into a batch tank 4. The quantity of fluid as drawn is predetermined so that a mixture of the desired concentration will result when the contents of a drum S of milk powder are added thereto. Such drum 5 is opened but the contents are not disturbed except by the insertion of a suction tube 6; so milk powder will not be spread as dust throughout the manufacturing establishment. The suction tube 6 has sufficient travel, by reason of its own flexibility or rotation in its ioints, to reach to the bottom of the drum 5.

The ingredient quantities being established at desired proportions, a batch tank valve 7 adjacent the bottom of the batch tank 4 is opened so as to permit the ow of the fluid from the batch tank 4 by gravity to a constant delivery pressure pump 8. In the present invention it has been found satisfactory, for relatively small scale product1on, to use a pump 8 having a rate of flow of 24,000 pounds per hour and 11/2 inch diameter sanitary pipe.

From the delivery pump 8 the fluid is conducted through a lead to a suction T 9. Forming the fluid inlet to the suction T 9 is a jet nozzle 10, shown in cross-section in Figure 2. A nozzle satisfactory for the system described may be formed of 1 inch sanitary tubing at its inlet end 11, and reduced taperedly to a diameter of 5A; inch at its outlet end 12. Such nozzles have been found to produce sufficient suction within the suction T 9 as, when supplied with fluid under pressures of 15 pounds to 20 pounds per square inch over atmospheric, will suck milk powder from the drum 5 at rates from 20 pounds to nearly 50 pounds per minute. The rate of flow is quite uniform once the nozzle shape is finally determined, and the fluid pressure and height of lift of the powder denitely set.

The sanitary suction tube 6 connects with the sanitary suction inlet 13 of the sanitary suction T 9 and communicates with a sanitary suction chamber 14 annularly surrounding the jet nozzle 10 and the fluid jet which emerges therefrom. Where the jet nozzle 10 is aligned substantially horizontally within the suction T 9, as shown in Figures 1 and 2, I have found it advisable to locate the suction inlet 13 at the upper side of the suction T 9. Any fluid which may drip from the nozzle 10 into the suction chamber 14 cannot therefore bring about a premature wetting of the milk powder at the suction inlet 13.

Milk powder is notoriously difcult to handle in the presence of moisture because when outer particles of powder are wetted they tend to seal up within them unwetted particles. Heretofore this quality of milk powder has been thought to require much agitation for mixing of the powder into the fluid and for the avoidance of large doughy aggregations of powder. One of the essential steps of the new process here described is to loosen the milk powder particles so that they separate from each other before wetting. This is done by the suction created in chamber 14 of the suction T 9 and by the resistance to suction formed by the force of gravity acting upon the individual milk particles. The suction tube 6 is therefore provided with a feed end 15 having a vertical rise, in which gravity helps to loosen the particles from each other. The feed end 15 is filled by the particles as they are sucked toward the suction T 9, but by loosened particles rather than by compacted ones. Such loosened particles are drawn into the chamber 14 and there separately entrained in and enveloped by the high velocity jet stream whose energy, as it emerges from the nozzle 10, is tremendous. They are mixed in the jet stream by its own force in the absence of air, into stable solution without any physical agitation and at a rate which has heretofore been thought impossible of achievement.

The mixture is then returned to the batch tank 4 through the three-way valve 2, which is shown in Figure l in position to permit such return ow. The fluid from the batch tank 4 may be re-circulated through the system by means of the constant delivery pump 7 and the return pump 16 until the desired quantity of the milk powder from the drum 5 has been drawn into the solution with fluid. lf only a small quantity of powder is being added to a large quantity of uid, a better degree of uniformity of the fluid solution may be achieved by continuing for a short period circulating the fluid through the system back to the batch tank, even after no powder is being added.

The fluid in solution constitutes the final product, ready for canning and sterilization. It may be drawn from the batch tank 4 in the system illustrated, by setting the three-way valve 2 in position connecting the return line 17 with the outlet line 18, and utilizing the pumps 7, 16.

The sole function of the return pump 16 is to return the uid passing out of the nozzle outlet 12 to the batch tank 4. Thus, this pump 16 may be of the positive displacement type; although a centrifugal pump, which agitates the Huid, may be used without disadvantage.

In Figure 3 is illustrated an alternative embodiment utilizing but one pump 7 which draws the fluid from the batch tank 4', raises the uid, and puts it under pressure before supplying it to the nozzle 10' of the suction T 9. In this embodiment the suction T 9' is located above the level of the batch tank 4 and the nozzle 10 points downward, so that the return ow to the batch tank 4 is accomplished. Milk powder from the drum 5 is raised through the vertical portion 1S of the suction tube 6', and is entrained and mixed into solution within the suction T 9 in the manner heretofore described. After a batch has been reconstituted, it is driven by the same pump 7 out through the outlet 18', the three-way valve 2' being first set to appropriate position. It may be noted that with the suction T 9' holding the jet nozzle 10' in vertically downward position, as shown in Figure 3, there is no danger of tluid dripping from the nozzle outlet into the end of the suction tube 6.

Using a high-velocity jet of fluid, I have found that there is no danger of clogging by reason of fluid dripping into the suction lead opening, or from normal variation in consistency of the milk powder being fed thereto. The force of the jet is not only sufficient to keep it entirely free from any tendency to clog, but also apparently suicient to disintegrate into particles any conglomerated masses of milk powder. The process has in these respects proved to be entirely reliable and stable.

The foregoing description has indicted the suitability of the process for reconstitution by batches of product. So precisely metered is the flow of the milk powder into the fluid, however, that continuous production is feasible, without recirculation, after the nozzle and pump ow characteristics have been established to give the desired mixture of ingredients. For example, with the set-up described the pump and nozzle being so balanced as to add 10% of milk powder to 90% of fluid, reconstituted skim milk of the consistency of evaporated skim milk can be produced at the suction T outlet by pumping fresh skim milk as the fluid and using powdered non-fat milk; and, if desired, a product equivalent to fresh skim milk can be produced at the suction T outlet by using water as the fluid. If the former product is produced, it can be made into the equivalent of evaporated filled milk by adding vegetable fat and synthetic vitamins, and

homogenizing.

By mnpmdutmem of.theabalamebetwssn thapump and the nozzle?, a somewhat greater proportion of milk powder may be; addedfso thabfvsina .ii/11.0.16; milk POWder witl1,.lwat er, `aproduct equivalent to whole milk, will be,` producedanthe'suction T outlet. `Using ,wholeJas,`

der ,withgwater to the consistency of whole ,milk and using powder so that the second time the resultant is equivalent to evaporated milk.

The principal advantage of the present invention is to provide flexibility to the dairy industry in utilizing milk powders, often available at low prices, and inexpensive equipment, to supplement or take the place of evaporating equipment. Thus, the following products are readily made, in the same manner as described, with modifications in ingredients as follows:

(1) The equivalent of condensed whole milk, by fortify ing cold whole milk with whole milk powder, using enough whole milk powder to obtain a final test of 25.9% total solids including 7.9% milk fat.

(2) The equivalent of condensed whole milk, by reconstituting 25.9% whole milk powder with 74.1% cold water.

(3) The above-described equivalent of condensed skim milk, by fortifying cold skim milk with enough non-fat milk powder to obtain a final test of 20% solids not fat.

(4) The equivalent of condensed skim milk, by reconstituting 20% non-fat milk powder with cold Water.

(5) The equivalent of evaporated lled milk, by fortifying cold skim milk with non-fat milk powder, adding vegetable fat and homogenizing, to obtain a final test of 26.15% total solids including 6% fat.

(6) The equivalent of evaporated filled milk, by reconstituting non-fat milk with cold water, adding vegetable fat and homogenizing, to obtain a nal test of 26.15% total solids including 6% fat.

(7) The equivalent of concentrated skim condensed milk, by fortifying cold skim milk with non-fat milk powder to such consistency as is desired.

(8) The equivalent of concentrated skim condensed milk, by reconstituting non-fat milk powder with cold water to such consistency as is desired.

While dairymen will appreciate the advantage of using cold fluids in these products, the process will, of course, function using fluids at higher temperatures, but without the same inhibition on bacterial development; and there is no reason why, considering the efficiency of the process, cold fluids should not be used in all the foregoing products.

A commercially-acceptable equivalent to evaporated milk must possessess good flavor, color, consistency, loW bacteria count, and must show no apparent sedimentation after standing, canned, for several months. All the products referred to herein have that full degree of acceptability for the milk products of evaporation of which they are equivalent in ingredients.

While throughout this specification and claims the term solution is used, it is recognized that milk, whether whole, evaporated or reconstituted is in some sense a solution, in some a suspension, and where milk fat is present, an emulsion. It is customary to apply the term solution to a reconstituted product, when no objectionable sedimentation occurs on standing. It is in this sense that the term is used herein.

For purposes of the claims, the term cold refers to uid at holding temperatures at which dairy products may desirably be kept to inhibit bacterial growth, presently considered to be approximately 40 F. It is to be distinguished from room temperature, approximately 70 F., at which attempts to reconstitute milk powder have heretofore been made, but not with success on a com- The term "'rnilkpr'oductsy of" evaporation?" refers to thosf'milkfproductswhich 'havebeen concentrated evaporation, including evaporated whole milk, 'skimY milk,

lled milk, -andV condensed milk, with 'or I, "ad-' ditirs insediata..

1. A process for mixing powdered milk into stable solution with a potable watery fluid, comprising the steps of establishing the temperature of a potable watery fluid at a safe holding temperature for dairy products, passing the fluid in a stream through a venturi T having a suction inlet, thereby accelerating the fluid flow and reducing the pressure of the fluid stream to a value below atmospheric pressure, whereby suction is created in the suction inlet of the venturi T, interposing a supply of milk powder between such suction inlet of the venturi T and the pressure of the atmosphere, by such suction, loosening its particles and drawing the separated particles of such milk powder into the accelerated stream, and entraining such milk powder particles into solution with the fluid stream.

2. A batch process for reconstituting powdered milk to a desired concentration with a supply of milk powder, comprising the steps of claim l, the supply of milk powder being first proportioned with respect to the supply of uid so that their mixture will be in the concentration desired, together with the additional step of recirculating the fluid through the T until the entire supply of powder has been entrained into and mixed uniformly with the supply of uid.

3. A process for separating from each other dry powder particles of a type having a tendency to cohere when moistened, and for bringing them into a uniform mixture with a liquid, comprising the steps of passing a stream of liquid through a mixing zone, accelerating the flow of said stream and thereby reducing the pressure in said mixing zone to sub-atmospheric pressure, utilizing such sub-atmospheric pressure to lift dry powder particles against the force of gravity and thereby loosen them from each other, further utilizing such sub-atmospheric pressure to draw the loosened particles into the mixing zone, and separately entraining the particles of powder Within the accelerated stream wherein said particles are enveloped without cohering and are uniformly intermixed within the accelerated stream.

4. A device for entraining and mixing within a fluid, powder particles which must be separated before being moistened, comprising means for supplying uid under greater than atmospheric pressure, a fluid conduit lead` ing therefrom to a reduced area orifice whereby fluid may be accelerated and its pressure reduced to less than atmospheric pressure, said orifice opening into a mixing chamber having a suction inlet in the region wherein such pressure is so reduced, and a liuid outlet and a podwer supply conduit extending from a point below the level of the orifice and communicating with the reduced pressure region above the level of the orifice, whereby powder may be drawn downwardly into said reduced pressure region from a powder supply, entrained and mixed with the accelerated fluid.

5. A device for entraining and mixing within a uid powder particles of a type which require loosening before admixture with a fluid and tend to cause foaming when so mixed, comprising means for supplying fluid under greater than atmospheric pressure, a suction venturi T connected therewith and adapted to accelerate the flow of uid therefrom and reduce its pressure to less than atmospheric pressure, the T including a mixing chamber having a suction inlet in the region wherein such pressure is so reduced, said inlet being above the 7 level of the uid stream inlet into the T, a powder supply conduit communicating with the suction inlet and having a rise portion whereby powder may be drawn up from a powder supply and the particles thereof loosened from each other, such loosened powder particles being 5 entrained and mixed in the mixing chamber with the accelerated fluid.

6. A device as dei-ined in claim 5, together with a batch tank from which such uid is supplied, and means communicating between said mixing chamber and batch tank 10 for returning the mixture to said batch tank.

UNITED STATES PATENTS Scott May 31, 1927 McGrael Apr. 28, 1936 Bradshaw et al. Oct. 29, 1940 Urquhart May 15, 1945 Haugh Sept. 18, 1945 North et al. Apr. 30, 1946 Keane June 14, 1949 Chrysler et al. Apr. 11, 1950 

1. A PROCESS FOR MIXING POWDERED MILK INTO STABLE SOLUTION WITH A POTABLE WATERY FLUID, COMPRISING THE STEPS OF ESTABLISHING THE TEMPERATURE OF A POTABLE WATERY FLUID AT A SAFE HOLDING TEMPERATURE FOR DAIRY PRODUCTS, PASSING THE FLUID IN A STREAM THROUGH A VENTURI T HAVING A SUCTION INLET, THEREBY ACCELERATING THE FLUID FLOW AND REDUCING THE PRESSURE OF THE FLUID STREAM TO A VALUE BELOW ATMOSPHERIC PRESSURE, WHEREBY SUCTION IS CREATED IN THE SUCTION INLET OF THE VENTURI T, INTERPOSING A SUPPLY OF MILK POWDER BETWEEN SUCH SECTION INLET OF THE VENTURI T AND THE PRESSURE OF THE ATMOSPHERE, BY SUCH SUCTION, LOOSENING ITS PARTICLES AND DRAWING THE SEPARATED PARTICLES OF SUCH MILK POWDER INTO THE ACCELERATED STREAM, AND ENTRAINING SUCH MILK POWDER PARTICLES INTO SOLUTION WITH THE FLUID STREAM. 